Mercedes Power Unit Hardware & Software

[BassVirolla]

Nevertheless, in a cross plane with four (or eight!) final exhaust pipes, you can do a decent impulse tuning job, even though tuned for a half or quarter the rpms. Obviously, not ideal for a racing NA engine.

We are going quite off topic in fact... Mods, feel free to delete if necessary.

It's very interesting. Why does Yamaha prefer a crossplane crankshaft for their Yamaha R1?

(...and I on think their Yamaha MotoGP bike too? Are Yamaha the only MotoGP team not using a V4 engine? How about Suzuki? Edit -- it seems Suzuki also uses an inline-four on their MotoGP but with a crossplane crankshaft and not the flatplane one like their road-going GSXR1000.)

I've read some time ago that it was a drivability thing.

https://www.yamahapart.com/crossplanecrankshaft

[Hoffman900]

Totally a driveability thing.

This gets into some interesting thoughts behind it. Doesn't reveal a lot, but enough:
https://www.motorsportmagazine.com/arti ... s-possible

Kurt Trieb was also part of BMW's F1 engine program in the early 2000s.

[djos]

Nevertheless, in a cross plane with four (or eight!) final exhaust pipes, you can do a decent impulse tuning job, even though tuned for a half or quarter the rpms. Obviously, not ideal for a racing NA engine.

We are going quite off topic in fact... Mods, feel free to delete if necessary.

It's very interesting. Why does Yamaha prefer a crossplane crankshaft for their Yamaha R1?

(...and I on think their Yamaha MotoGP bike too? Are Yamaha the only MotoGP team not using a V4 engine? How about Suzuki? Edit -- it seems Suzuki also uses an inline-four on their MotoGP but with a crossplane crankshaft and not the flatplane one like their road-going GSXR1000.)

That’s easy, it makes it easier to ride on the limit out of corners (on race tracks) because it doesn’t work the rear tire as hard.

[b2bL44]

https://www.motorsportmagazine.com/arti ... ngines-mph

Super-cool approach may bring power surge to Mercedes engines – MPH

Have Mercedes found yet another brilliant innovation to squeeze even more horsepower out of its engine?

You see that great big blister on the side of the engine cover of the Mercedes W12 and Aston Martin AMR21? That’s to clear space for what is an unusually large intake plenum for the Mercedes power unit. It’s been on both cars since their pre-season introduction. It’s not a new thing. The McLaren MCL35M and Williams FW43B are also Mercedes-powered but their engine covers are shaped very differently, with a stepped profile, wider at the bottom, which would allow the plenums to be accommodated without the bulge.

When James Allison referred to the bulge at the W12’s launch, he said, “There’s been a big investment by our friends at HPP to redesign the plan of the intake system of the engine, re-tune the engine around that, and squeeze a lot more horsepower out of the power unit as a consequence.”
The new power unit, it was whispered at the time, had a system whereby an amount of coolant could be taken from the main system and super-cooled as it was put into the walls of the inlet plenum. It would then be released once more back into the main system after having done its brief job. That job being to significantly cool the air within the intake plenum, increasing its density and therefore its combustibility. But only for a brief period as the thermal transfer between the cool walls and the warmer air took place. Thereafter that no-longer-super-cooled coolant would be released back into the system and the engine would revert to normal power. In order to effectively allow thermal transfer to a fast-moving gas, the plenum would need not to be fashioned from the usual carbon fibre (which is a very poor conductor of heat). But a ceramic would work very well and an internal matrix of surfaces within the walls to increase the surface area over which the super-cooled liquid will pass can be imagined.

The regulations insist that the air in the plenum must be at least 10-deg C higher than the external ambient temperature, as an average over the race. But getting close to that without going under the permitted limit, given the huge variations in operating conditions, would be no easy task. Such a system would allow you to do that, would allow you to claim back some of any surplus ‘allowance’ that had built up while you ensured legality, with a quick blast of ‘super-cooled’ power (the air would not be super-cooled, merely the liquid which was cooling the walls).

The system could also be used to address the fact that as you increase the flow of the inlet charge at maximum pressure (under full acceleration), you inadvertently also increase its temperature. This extra cooling just before the air is mixed with the fuel may simply bring it back down to its normal temperature.
Of course the super-cooled walls theory may just be a red herring and the massive plenum may simply be to give variable size of the effective plenum by having different routes through it according to whether quick response or full capacity was required (a small plenum works best for response but will run out of capacity at high speed). This would give a better initial acceleration than a conventional ‘compromise size’ plenum, before then merging to normality just as would a super-cooled plenum.The teams analyse each others’ GPS traces to the nth degree and Red Bull has recently made the observation that the Mercedes gives such sudden brief power bursts on acceleration out of a corner, with the power then tailing off to ‘normal’. This has been used by Red Bull’s Dr Marko to ‘explain’ the change in competitive order in Merc’s favour between the France/Austria races and Silverstone/Hungary and the team has made a query to the FIA about the placement of the regulation FIA temperature sensors within the Mercedes plenum. The implication being they believe it might be possible those sensors are under-reading the actual temperature if they are not close to those supposedly super-cooled walls.

In its effect on the changing of the mid-season competitive order, the plenum story fails to account for the fact that the system was already there pre-season (or the fact that Red Bull qualified on pole 0.3sec faster than Mercedes at Spa last week, or the fact that there is no such pattern in the competitive order of Aston, McLaren and Williams).

The plenum innovation, whatever its actual mechanism, is not a new thing. But it’s typical F1 brilliance in how it pushes at envelopes that were believed way more rigid than they turned out to be. Some original thought has squeezed yet-more energy efficiency from that ancient old dinosaur, the internal combustion engine.

In addition, important to note from Mark Hughes in the comments:

There is absolutely no suggestion that Mercedes’ plenum idea is not legal. None at all.

It is totally different to, for example, cheating the fuel flow regulations. Or having traction control software when traction control was banned. Or having an oversize engine.

But Red Bull is asking the FIA a legitimate question - are the sensors in a place where they will accurately record the temperatures within such a system?

[Tommy Cookers]

I've read some time ago that it was a drivability thing.
https://www.yamahapart.com/crossplanecrankshaft

hooey !
it's a smokescreen - and brilliant advertising
the crossplane effects described have no effect at the back wheel - because they can't reach the back wheel
the back wheel is inherently isolated by transmission shafts etc from such events at eg 300 cycles/sec
(and the back tyre is a gas-filled bag)
cheeky Furasawa (retiring M1 program boss) was an electronics engineer not a mechanical engineer
electronics works because a stage's output isn't loaded by input to the following stage (the opposite of MotoGP)

the Honda paper Hoffman linked P187 shows 'pickup' response vs peak was influenced by exhaust (and induction) design
this is where eg crossplane vs conventional has an effect
Treib is saying roughly the same thing
Gordon Blair (he consulted for Ducati MotoGP) wrote the same thing

the great Mercedes induction-cooler controversy may also be a smokescreen (says Motor Sport)

[_cerber1]

[BassVirolla]

I've read some time ago that it was a drivability thing.
https://www.yamahapart.com/crossplanecrankshaft

hooey !
it's a smokescreen - and brilliant advertising
the crossplane effects described have no effect at the back wheel - because they can't reach the back wheel
the back wheel is inherently isolated by transmission shafts etc from such events at eg 300 cycles/sec
(and the back tyre is a gas-filled bag)
cheeky Furasawa (retiring M1 program boss) was an electronics engineer not a mechanical engineer
electronics works because a stage's output isn't loaded by input to the following stage (the opposite of MotoGP)

the Honda paper Hoffman linked P187 shows 'pickup' response vs peak was influenced by exhaust (and induction) design
this is where eg crossplane vs conventional has an effect
Treib is saying roughly the same thing
Gordon Blair (he consulted for Ducati MotoGP) wrote the same thing

the great Mercedes induction-cooler controversy may also be a smokescreen (says Motor Sport)

I totally agree with the mojo and marketing excercise with the power-pulse-to-wheel. Nevertheless, with the "pick-up" (low rpms torque delivery) obviously has to be an effect in drivability. This said, I've never rode a motorbike, with independence of its crankshaft.

[Hoffman900]

I've read some time ago that it was a drivability thing.
https://www.yamahapart.com/crossplanecrankshaft

hooey !
it's a smokescreen - and brilliant advertising
the crossplane effects described have no effect at the back wheel - because they can't reach the back wheel
the back wheel is inherently isolated by transmission shafts etc from such events at eg 300 cycles/sec
(and the back tyre is a gas-filled bag)
cheeky Furasawa (retiring M1 program boss) was an electronics engineer not a mechanical engineer
electronics works because a stage's output isn't loaded by input to the following stage (the opposite of MotoGP)

the Honda paper Hoffman linked P187 shows 'pickup' response vs peak was influenced by exhaust (and induction) design
this is where eg crossplane vs conventional has an effect
Treib is saying roughly the same thing
Gordon Blair (he consulted for Ducati MotoGP) wrote the same thing

the great Mercedes induction-cooler controversy may also be a smokescreen (says Motor Sport)

I totally agree with the mojo and marketing excercise with the power-pulse-to-wheel. Nevertheless, with the "pick-up" (low rpms torque delivery) obviously has to be an effect in drivability. This said, I've never rode a motorbike, with independence of its crankshaft.

It does, but it's a pressure dynamics issue, and not so much an crankshaft angular velocity change issue due to power pulses.

In our world (road racing cars) it matters in terms of shift recovery, but it's not so much dealt with via firing order changes, but really working the exhaust and intake lengths, and in the case of the exhaust, diamaters. With carburetors, I'm even looking back 500+rpm below our lowest point, because bad pressure dynamics there, may effect jet signal at recovery... remember a carburetor works off pressure differentials, it only knows what just happened. When you shift, the whole pressure wave dynamics of an engine reset to your shift drop point, the faster it can recover the faster it can re-accelerate.

I have no doubts the Mercedes plenum / cooling issue is a smoke screen. The plenum cooling trick rumor floating around feels "gimmicky".

[PlatinumZealot]

So Honda is saying that Mercedes low speed acceleration is too good, so it must be their engine making more torque than anyone elses?

Vapour compression is not allowed right?

Are heat pipes allowed?? Whis is basically two phase cooling. Low boiling point water in the plenum walls, gets heated by intake, the vapour moves to a heat sink where it is condensed and water returns to the chamber walls again.

This is a genius idea if viable. Doesn't break the rules I think.

RedBull seems to be complaining that Mercedes has deceived the FIA with the location of the sensor. The plenums are quite small and turn down to the runners quickly.. Not sure how much more cooling surface is in the actual runners themselves.

Very weak case I think.

[taperoo2k]

RedBull seems to be complaining that Mercedes has deceived the FIA with the location of the sensor. The plenums are quite small and turn down to the runners quickly.. Not sure how much more cooling surface is in the actual runners themselves.

Very weak case I think.

It's worth remembering Red Bull will be developing their own PU's soon. You can either view it as Red Bull desperately trying to reduce the performance of the Mercedes PU or it's Red Bull on a fishing expedition to gain a bit more info on how the Mercedes system works and if it's legal, for future development avenues. Could be either or the mix of the two.

[Hoffman900]

Exactly. It’s either a phishing expedition or asking for a rules clarification before they go down that path.

[toraabe]

Nevertheless, in a cross plane with four (or eight!) final exhaust pipes, you can do a decent impulse tuning job, even though tuned for a half or quarter the rpms. Obviously, not ideal for a racing NA engine.

We are going quite off topic in fact... Mods, feel free to delete if necessary.

It's very interesting. Why does Yamaha prefer a crossplane crankshaft for their Yamaha R1?

(...and I on think their Yamaha MotoGP bike too? Are Yamaha the only MotoGP team not using a V4 engine? How about Suzuki? Edit -- it seems Suzuki also uses an inline-four on their MotoGP but with a crossplane crankshaft and not the flatplane one like their road-going GSXR1000.)

That’s easy, it makes it easier to ride on the limit out of corners (on race tracks) because it doesn’t work the rear tire as hard.

Exactly. It's like the 500 two stroke big bang engine. The uneven firing order makes the tyre retain the grip between the pulses.

[gruntguru]

Are heat pipes allowed?? Whis is basically two phase cooling. Low boiling point water in the plenum walls, gets heated by intake, the vapour moves to a heat sink where it is condensed and water returns to the chamber walls again.

Pretty sure two phase cooling is not allowed.

Sub-cooling of the charge could be done using the Porsche method which is essentially a vapour compression technique - boost higher than you need - intercool to near ambient temp - expand to the desired boost pressure and enjoy the associated temperature reduction. Similar to air cycle refrigeration used in some aircraft - with the exception that the expansion is done in a turbine for even lower temperatures and some energy recovery.

[Hoffman900]

Are heat pipes allowed?? Whis is basically two phase cooling. Low boiling point water in the plenum walls, gets heated by intake, the vapour moves to a heat sink where it is condensed and water returns to the chamber walls again.

Pretty sure two phase cooling is not allowed.

Sub-cooling of the charge could be done using the Porsche method which is essentially a vapour compression technique - boost higher than you need - intercool to near ambient temp - expand to the desired boost pressure and enjoy the associated temperature reduction. Similar to air cycle refrigeration used in some aircraft - with the exception that the expansion is done in a turbine for even lower temperatures and some energy recovery.

I would be surprised if they all aren’t doing that to some degree. It’s not exactly a secret or new.

[Just_a_fan]

Are heat pipes allowed?? Whis is basically two phase cooling. Low boiling point water in the plenum walls, gets heated by intake, the vapour moves to a heat sink where it is condensed and water returns to the chamber walls again.

Pretty sure two phase cooling is not allowed.

Sub-cooling of the charge could be done using the Porsche method which is essentially a vapour compression technique - boost higher than you need - intercool to near ambient temp - expand to the desired boost pressure and enjoy the associated temperature reduction. Similar to air cycle refrigeration used in some aircraft - with the exception that the expansion is done in a turbine for even lower temperatures and some energy recovery.

I would be surprised if they all aren’t doing that to some degree. It’s not exactly a secret or new.

And might be why the FIA specify that the temperature must be (ambient + 10deg C) in order to limit / prevent it.